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This review covers the use of Prussian blue and its analogues as sacrificial templates and the adopted strategies to produce new materials with diverse compositions, structures and morphologies.

International audience; Pesticide sensing is an important object of study due to its increasing use worldwide. Herein, we report a SERS study of 4-nitrophenol (PNP), which is product of neutralization processes of various pesticides such as Paraoxon, and can be used as a target molecule for monitoring. PNP is also widely used in the chemical industry and due to its high toxicity is considered a concerning pollutant. The sensing was carried out with a reduced graphene oxide nanocomposite functionalized with cysteamine and Ag nanoparticles (rGOSHAg), and compared with raw reduced graphene oxide and a commercial SERS substrates (SERStrate (TM)). A mechanistic evaluation was also carried out, focused in the degradation of PNP caused by the different exciting laser lines, evidencing the PNP dimerization in substrates containing Ag NPs (under 532 nm laser), which has important outcomes for sensing purposes. The nanocomposite rGOSHAg presented the highest sensitivity towards PNP, detecting concentrations as low as 10(-6) mol L-1 and with a high potential for field applications and real-time measurements of molecules commonly present in pesticides and industrial contaminants.

Thin film technology is pervasive for many fields with high impact in our daily lives, which makes processing materials such as thin films a very important subject in materials science and technology. However, several paramount materials cannot be prepared as thin films through the well-known and consolidated deposition routes, which strongly limits their applicability. This is particularly noticeable for multi-component and complex nanocomposites, which present unique properties due to the synergic effect between the components, but have several limitations to be obtained as thin films, mainly if homogeneity and transparence are required. This review highlights the main advances of a novel approach to both process and synthesize different classes of materials as thin films, based on liquid/liquid interfaces. The so-called liquid/liquid interfacial route (LLIR) allows the deposition of thin films of single- or multi-component materials, easily transferable over any kind of substrate (plastics and flexible substrates included) with precise control of the thickness, homogeneity and transparence. More interesting, it allows the in situ synthesis of multi-component materials directly as thin films stabilized at the liquid/liquid interface, in which problems related to both the synthesis and processing are solved together in a single step. This review presents the basis of the LLIR and several examples of thin films obtained from different classes of materials, such as carbon nanostructures, metal and oxide nanoparticles, two-dimensional materials, organic and organometallic frameworks, and polymer-based nanocomposites, among others. Moreover, specific applications of those films in different technological fields are shown, taking advantage of the specific properties emerging from the unique preparation route.

In celebration of the excellence and breadth of Latin American research achievements across the chemical sciences, we are delighted to present an introduction to the themed collection, Celebrating Latin American talent in chemistry.

Electrodes combining battery and supercapacitor materials are an alternative to enhance energy and power densities in energy storage devices. Herein, a material of graphene modified with the trirut...

We report a simple and effective route to synthesize, disperse, exfoliate and process different molybdenum-based 2-dimensional (2D) materials. Starting from a reaction between ammonium molybdate and ammonium sulfide solutions, a powder consisting of a mixture between amorphous molybdenum oxide and sulfide is obtained. By tuning the atmosphere and the temperature, different compositions can be prepared by thermal treatment of this sample: heat treatments in ambient atmosphere produce MoO3 with different morphologies, controllable according to the chosen temperature. On the other hand, heat treatments in inert atmosphere produce mixtures between crystalline 2D MoS2 and MoO3. Further handling of these mixtures with acetonitrile separates the components due to the different solvent/solid affinities, with the layered MoS2 becoming homogeneously dispersed, and the MoO3 agglomerating as a solid easily removed by centrifugation. The resulting sulfide dispersions in acetonitrile present high stability, and they are constituted by exfoliated MoS2, which means that acetonitrile is a tri-functional agent, separating the sulfide/oxide mixture, exfoliating the sulfide and stabilizing the dispersion. The MoS2 dispersions were used to produce homogeneous, freestanding and transparent thin films through the liquid-liquid interfacial route, which were easily deposited over different substrates and characterized by different techniques.

A detailed and multi-technique study on the kinetics and mechanism of the electrodeposition of Prussian blue (PB) over iron filled-carbon nanotubes (CNTs) thin films is presented here. PB is electrochemically synthesized through a heterogeneous reaction between iron species encapsulated into CNTs and ferricyanide ion in aqueous solution. The reaction was followed by a combination of in-situ or ex-situ measurements through UV–Vis spectroscopy, cyclic voltammetry, Raman spectroscopy and scanning electron microscopy. The analysis of the evolution of a new parameter that we called coverage ratio as well as an innovative way to associate the data extracted from cyclic voltammetry with the electrochemical reaction, are introduced by the first time. Similar response vs. time profiles are obtained from absorbance, charge, current, band intensity in Raman spectra, particle size, and coverage ratio, yet providing different aspects of the growth mechanism. Electrochemical data demonstrates an initial mixed control process related to the iron releases from the CNTs cavities and nucleation, followed by a diffusion limited regime on the growth of PB. Spectroscopic data indicates pseudo-first order kinetics, dependent on ferricyanide concentration, and the rate limited by the iron releases from the CNTs. Both particle size of PB and coverage ratio show a progressive nucleation of PB corroborating the proposed mechanism. Raman data also confirm the PB growth rate over the CNTs walls and evidence of PB/CNT interactions during voltammetric cycles. This multi-technique approach gives insights on different aspects of PB electrodeposition and can be extended to a wide class of different materials.

A simple and versatile route to synthesize nanocomposite thin films containing polythiophene, gold nanoparticles and carbon nanotubes is demonstrated. The strategy is based on a liquid-liquid interfacial reaction, in which polythiophene and gold nanoparticles are concomitantly synthesized through a reaction between an aqueous solution of tetrachloroauric acid and a n-hexane solution of thiophene containing carbon nanotubes previously dispersed. The three-component nanocomposite is obtained directly as a thin and homogeneous film, self-assembled at the liquid-liquid interface, and easily transferable to ordinary substrates. Different reaction times were investigated, and the materials were characterized by several techniques, such as SEM, TEM, profilometry and EDS to inform about the morphology and the elementary composition, FTIR, Raman, TGA, UV–Vis and DRX about the structure of the materials and the electrochemical properties were investigated by cyclic voltammetry. The presence of carbon nanotubes accelerates the reaction, yielding greater amount of product when compared to similar reactions conducted without the carbon nanotubes. The proportion between the components, amount of products and film thickness can be controlled by the reaction time. It is observed that the amount of both polythiophene and gold nanoparticles increases with the increasing reaction time, inducing the formation of polymer agglomerates over de carbon nanotubes and the anisotropic growth of gold nanoparticles. The presence of CNT increases the electrochemical stability of the films when compared to similar ones without CNT. The potentiality of the prepared nanocomposite as electrochemical sensor was evaluated for voltammetric determination of dopamine. Best results were found for a PT/Au/CNT film prepared after 4.5 h of reaction, with a limit of detection of 0.69 μmol L−1.

Aqueous dispersions of fullerene C60 were prepared from fulleride solutions in tetrahydrofuran, followed by air oxidation, transfer to water and solvent evaporation. Fulleride exposition to air produces charged fullerene dispersions in THF that can be transferred to water to produce aqueous fullerene dispersions, stable for months.

Thin films of multiwalled carbon nanotubes/polyaniline nanocomposites (CNT/PAni) were synthesized through the liquid/liquid (L/L) interfacial route, deposited over glass substrates, and evaluated through cyclic voltammetry and amperometry as electrochemical sensor, using L-ascorbic acid as probe. Films with three different CNT/PAni ratios have been prepared. After the spectroscopic and morphological characterization, the electrochemical sensitivity towards L-ascorbic acid was evaluated and compared with similar sensors prepared from neat multiwalled carbon nanotubes (MWCNT) or neat polyaniline (PAni). The nanocomposite film that presented the best nanotube dispersion through the polymeric matrix presented the higher sensor sensibility, 0.237 µA (µmol L−1)−1 and a limit of detection (LOD) of 7.91 µmol L−1. These results evidenced a synergistic effect among the components, and the best response depended on strict control of the polyaniline matrix distribution surrounding the nanotubes.

Thin films of nanocomposites between carbon nanotubes (CNTs) and three different hexacyanometallates (HCMs) – Prussian blue, ruthenium purple (RP) and cobalt hexacyanoferrate (CoHCFe) - were synthesized with different cations: K+, Na+ and Li+. The effect of the cations in both the structure and properties of the HCMs was evaluated by several characterization techniques, showing that the nature of the cation is directly related to the size of the channels in the produced HCM structure, as well as to the defect content, the electrochemical behavior, the electrochemical stability and the strength of the interaction between the HCM and the CNTs. Due to the large hydrated radius, Li+ produced the more defective and less stable HCMs, while the HCM synthesized with Na+ had large porous and organized structure. All those factors deeply affect the performance of the different films when applied as cathodes for aqueous potassium-, sodium- and lithium-ion secondary battery, which depends on the relationship between the size of hydrated ion and the lattice of the HCM structure. The discharge profile and capacity for RP is reported by the first time. CoHCFe-based composites achieved capacities up to 150 mAh g−1 at 0.67 A g−1 rate, with retention of 90% after 2000 cycles.

We present the unprecedented application of a black phosphorus-based nanocomposite as an electrode for aqueous Na-ion batteries under ambient conditions. An impressive specific capacity of up to 200 mA h g-1 was reached after 50 cycles in a NaCl aqueous solution used as a supporting electrolyte. Post-characterization indicated the integrity of the black phosphorus.

A rapid and simple method for voltammetric determination of rifampicin (RIF) using a glassy carbon electrode (GCE) modified with nanostructured nickel hexacyanoferrate (NiHCF) was developed. The sensor was prepared through an unusual method to NiHCF electrosynthesis, starting from nickel nanoparticles previously deposited on the surface of different electrodes (glassy carbon, ITO and gold electrode) under potentiodynamic conditions. X ray diffractograms of Ni nanoparticles thin film were obtained for different stages of NiHCF films formation indicating a homogeneous distribution throughout the substrate with a mean size around 40 nm and an irregular shape. EQCM studies showed that the nature of cations can promote strong alterations on the voltammetric and microgravimetric profile during the growth of NiHCF due to the ion transport mechanisms of redox reactions. Both voltammetric and microgravimetric behavior were studied in the presence of sodium, lithium and potassium ions and the best responses were found using potassium ions as supporting electrolyte. The presence of RIF promoted a decrease in the cathodic peak current of NiHCF, suggesting an interaction between the antibiotic and Ni species presented at the electrode surface. The variation in the current signal was proportional to the RIF concentration and it was adopted for its quantification, allowing the construction of a linear analytical curve from 5.0 × 10−6 to 5.0 × 10−4 mol L−1 with a limit of detection of 2.6 μmol L−1. The method was successfully applied for RIF determination in simulated human urine samples with good agreement between the added and recovery values.

Chemical security has been a hot topic over several years, especially involving organophosphates (OP), which are related to organophosphorus chemical warfare and pesticides. The main challenges are to develop efficient ways to destroy stockpiles of these materials and also to monitor their presence in the field or food. A promising approach in this sense is the targeted design of catalysts that can react with OP and degrade them. Herein, we present a summary of some recent advances towards OP detoxification and monitoring that involves four different approaches: (i) How? Understanding the mechanism: thorough mechanistic elucidation and design of an ideal catalytic scaffold; (ii) Nanocatalysts and sensors: rational functionalization of carbon nanomaterials leading to nanocatalysts as powder and thin films. A surface-enhanced Raman scattering (SERS) sensor for OP was also obtained combining the functionalized material with silver nanoparticles; (iii) Catalysts from waste: reuse of rice husk waste as well as waste derived from the cheap gum arabic for developing biocatalysts that have high added-value and are environmentally friendly; (iv) A simple sensor: a simple, cheap and compact homemade colorimeter that can be used as a colorimetric sensor for detecting quantitatively various compounds, including pesticides.

Thin films of iron-filled carbon nanotubes prepared through the liquid/liquid interfacial method were modified with a mixture of hexacyanometallates (HCMs) Prussian blue and ruthenium purple. Two different approaches were used in order to obtain both materials in the composites, based on a direct reaction starting from a mixture of both precursors or a step-by-step deposition of each compound. The modified films were characterized by cyclic voltammetry, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and UV-Vis spectroscopy, confirming the formation of a mixture of HCMs in both methods of synthesis. Stability studies were evaluated in different supporting electrolytes, and composites presented good performances due to carbon nanotube stabilization. Electrochromic properties were also evaluated for selected composites, showing high electrochromic efficiency and stability.

Generation of hydrogen is one of the greatest challenges nowadays, especially chemically obtaining from the simple, straightforward borohydride hydrolysis reaction. Herein we are interested in this reaction for producing hydrogen using various nanocatalysts which are derived from graphene (reduced graphene oxide, rGO) and combined with metal-based nanoparticles (Ag, Ni and Ni(OH)2). Overall, four promising catalysts were obtained using the liquid–liquid interfacial route in order to obtain highly homogeneous thin films. We highlight the novelty in employing thin films for the generation of hydrogen gas, in which the reaction kinetics was thoroughly elucidated, obeying first-order profiles. In fact, very high catalytic activity was observed using low amounts of nanocatalysts (∼0.1–0.8 mg), with the maximum rate of hydrogen production reaching nearly 33 × 103 mL−1 min−1 g−1. rGO/Ni nanocomposites are reported here for the first time, which also showed the most prominent activity. The isolated components alone were not efficient, evidencing the synergism in the nanocomposites produced. Finally, the nanocatalysts were recycled for up to 10 consecutive cycles, without losing activity. Various characterization techniques were performed during the reactions and after the reuse and confirmed that the typical nature of the composites remains intact.

Promoting efficient organophoshate (OP) destruction has been of increasing interest, mainly due to their highly toxic nature and broad use as agrochemicals and chemical warfare. It is known that OP destruction can only be accomplished in the presence of catalysts, since they are knowingly stable. Hence, multifunctional materials have been targeted for this purpose since they can combine catalytic sites with features that enable easy handling, sensor projection for monitoring misuse and even large-scaled detoxification methods. Herein, we developed nanocatalysts derived from graphene oxide, which comprises reactive imidazole groups anchored by covalent functionalization. Two approaches were adopted: (i) a mild aqueous reaction leading to a powder, namely GOIMZ1; and (ii) a liquid/liquid interfacial functionalization, resulting in the thin film GOIMZ2. The nanocatalysts were applied in the destruction of OP and in the case of the toxic pesticide Paraoxon, impressive rate enhancements were obtained (10 8-fold). Both catalysts were consecutively recycled, maintaining overall characteristics. We highlight the feasible handling of the nanocatalysts, that in the case of the powder, it can be easily filtered, washed and reused. For the thin film, the handling is even more practical, since it can be immersed in the contaminated media and separated easier than the powder. Overall, we show novel imidazole-derived nanocatalysts with promising catalytic efficiency towards OP destruction, which have potential for projecting sensors and detoxification processes, especially with the thin films.

The way carbon nanotubes can modify the charge transport of organic materials may open opportunities for new uses. However, the understandings of many intrinsic physical properties associated to those changes are still poor. Here, we report our investigation on the properties of (PAni) and PAni/carbon nanotubes (CNTs) composites obtained by innovative interfacial polymerization method at room temperature. We have used spectroscopic methods (XPS, Raman) and microscopy (SEM) to obtain relevant parameters to combine with our electrical modeling and describe properly the transport characteristics of neat polymer and its composites with carbon nanotubes in different ratios. The devices were prepared in planar field effect transistor (FET) geometry to study the tunneling injection of charge carriers under the influence of the vertical component of a crossed electric field. We found that the tunneling injection is significantly improved using the PAni/CNT composite. This effect is related to morphological changes of the PAni film synthesized in the presence of CNTs, where the PAni polymerization on CNT's surface produces tubular structures covering them. Due to the CNT's high aspect-ratio, there is electric field amplification near to their tips that enhances the tunneling injection from the metallic contacts under the influence of the vertical field. We propose a theoretical model that can predict the electric field intensity of the transition. The number of tube's tips with different amplification factors (β) produces different regimes of tunneling injection in samples with moderate CNT concentration. We then propose a theoretical model that can predict the electric field intensity of the transition between those regimes: essentially it happens when the tunneling current produced by a few junctions with strong β is greater than the current produced by the higher number of junctions with low β. However, as the CNT density increases, the enhancement of the tunneling injection decreases due to electric field screening.

Here, composites based on carbon nanotubes and polyaniline films were tested as ammonia gas sensors with three different doping approaches (sulfuric acid, camphorsulfonic acid and m-cresol). The polyaniline high sensitivity to ammonia combined with the stability of the carbon nanotube increased the sensors reproducibility when compared to a regular polyaniline. The sensor in which the doping was performed by camphorsulfonic acid, presented the best sensor response for ammonia gas (418%) when compared to the others. This result is addressed to the better polymer configuration achieved by this procedure. The device's operation in low concentrations of ammonia indicates a strong adsorption process whit a limit of detection of 4 ppm.

The present work describes the synthesis of a nanocomposite between carbon nanotubes and gold nanoparticles through modified Brust-Schiffin route. Observations by XRD, TEM and TGA techniques showed an uniform, well-distributed and non-agglomerated dispersion of gold nanoparticles (7 ± 4 nm of average size) completely loaded onto MWCNTs surface. After further structural characterizations, the nanocomposite was casted onto a glassy carbon electrode and characterized by cyclic voltammetry. A seven-fold density current enhancement was observed, provided by the high superficial electroactive area of the active material. Sensing properties of so-synthesized nanocomposite were tested for dopamine detection in presence of ascorbic and uric acid by square wave voltammetry. After analytical parameters optimization, the dopamine-sensor presented linear range of 4.8 × 10 −7 –5.7 × 10 −6 mol L −1 with detection and quantification limits of 7.1 × 10 −8 and 2.4 × 10 −7 mol L −1 respectively and high sensitivity. The proposed method was applied in synthetic cerebrospinal fluids samples and the detection of DA in presence of potentially interferences in real samples was performed with satisfactory results.

Anchoring different functional groups on graphene may modulate and broaden its application, providing free groups to act for example as catalytic sites or for metallic nanoparticles (NPs) passivation. In this work, two novel approaches, based on the liquid/liquid (L/L) interfacial method, were used to obtain thiolated graphene oxide (GO) thin films rationally modified with cysteamine, through stable amide bonds, with different degrees of functionalization. In addition, nanocomposites of the functionalized film with silver nanoparticles (Ag-NPs) were obtained by the direct heterogeneous reaction of Ag+ cations with the films. The functionalized films were applied as nanocatalysts for organophosphate degradation, as SERS substrates and finally as a SERS-based qualitative sensor for nitrophenols. The thin film nanocomposites presented high performance in the detection of 4-aminothiophenol with enhancement factors up to 108. Moreover, the thiolated thin films were effective catalysts for degrading organophosphates such as the toxic pesticide Paraoxon, which presented impressive catalytic activity (106-fold). Elegantly, we managed to detect by Raman spectroscopy the degradation product adsorbed on the nanocomposite catalyst, hence achieving a SERS sensor for nitrophenol. Thus, we report for the first time the synthesis of functionalized graphene-based thin films through the interfacial route and their nanocomposites with Ag-NPs, along with their multiple applications. In fact, tailoring such multifunctionalities is particularly interesting for the development of sensors and detoxifying agents to monitor and eradicate abusive uses of toxic organophosphorus substances.

This work describes the application of a glassy carbon electrode (GCE) modified with imidazole functionalized carbon nanotubes (CNT-H-IMZ) for Paraoxon (PX) determination in samples of commercial, fresh and 100% orange juice. Homemade multi-walled CNTs were treated according to the Hummers procedure to oxidize graphite and later chemically functionalized with imidazole groups. Modified electrodes with CNT-H-IMZ presented a high peak current of PX reduction and an electrocatalytic effect in comparison to the other electrodes. This behavior was associated with the synergistic contribution of IMZ and CNT that increases the electrochemical activity of PX. Repeatability and reproducibility studies showed that the relative peak current values did not show significant differences between them, less than 10%, and it was possible to define that the diffusional process is the mechanism that limits the electrode mass transport. After the optimization of parameters inherent to the methodology and the voltammetric technique, the proposed device presented a linear region of 1.0 to 16.0 μM−1 (R2 = 0.99), presenting LOD and LOQ as 120 and 400 nM−1, respectively. The method proposed was successfully applied to PX determination in spiked samples.

The functionalization of carbon nanotubes (CNTs) has long been a challenge due to the low reactivity of CNTs. Herein we present a novel approach to covalently functionalize CNTs directly on the carbon surface with three different monomers of conductive polymers. A covalently linked polymeric nanocomposite derived from polypyrrole was also obtained. Highly reactive single-walled carbon nanotube (SWCNT) salts were functionalized with the monomers: 3-bromothiophene, 3-acetylthiophene and 1-(2-bromoethyl)-1H-pyrrole. After the functionalization, a “grafted from” approach was used to polymerize the pyrrole-derived SWCNTs and obtain a covalently linked polymeric nanocomposite. All samples were characterized by X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy, and infrared and Raman spectroscopy. Overall, the results evidence the efficiency of the covalent functionalization directly on the skeleton of the SWCNTs, followed by the polymerization and formation of a novel covalently linked nanocomposite. These materials can benefit future optimal applications such as supercapacitors and artificial muscles.

A novel methodology to prepare stable aqueous dispersions of raw single- and multi-walled carbon nanotubes is reported, based on dispersions previously prepared in tetrahydrofuran containing a phenol that donates electrons to nanotubes and provides colloidal stability through electrostatic repulsion. A proposed mechanism for the stabilization of the dispersions is presented. Conductive and transparent thin films are prepared through a liquid/liquid interfacial route starting from these dispersions.

Rubber nanocomposites are widely used in tires, technical parts, and consumer goods where elasticity is an important requirement. Incremental as well as radical innovations require developments in rubber compounding with the other materials needed to achieve the desired properties. Rubber compatibility with reinforcing agents depends on the interactions producing low interfacial tension at the polymer–particle interface that is achieved through previous structural and chemical modification of particles and rubber. Moreover, mechanochemical reactions take place during rubber compounding that can also make a positive contribution to rubber–filler low interfacial tension. This chapter concentrates on the interactions at the rubber interfaces with carbon particles: carbon black, nanotubes, graphene, graphene oxide, and graphite nanoplatelets. The contribution of the recently acknowledged electrostatic interactions and its importance to assemble different functional particles is presented, drawing from the results that have revealed the nanocomposite character of natural rubber and from analogous systems.

Aspuru-Guzik, Alán et al., To mark the occasion of Nature Chemistry turning 10 years old, we asked scientists working in different areas of chemistry to tell us what they thought the most exciting, interesting or challenging aspects related to the development of their main field of research will be — here is what they said.

Undoubtedly, the chemical element carbon is strategic for the development of any country and herein we show some specific impacts in the economical, industrial and scientific sovereignty of Brazil, with emphasis on sp2 carbn structures, namely graphite, carbon black, carbon nanotubes and graphene. Brazil comprises the second greatest natural reserve of graphite worldwide and ranks as third in world production. Carbon black also has important industrial impact in Brazil, especially in the automobile industry, specifically in tires. Some of world leading companies in the production of carbon black are installed in Brazil. Finally, carbon nanotubes and graphene are addressed as the next generation of materials that have and will have great impact in the next years. Their impressive properties have enabled innumerous commercial products worldwide and Brazil already stands out with some innovative initiatives. Indeed, Brazil has installed capacity in universities and research institutes to meet and foster demands in the area, and can be competitive worldwide.

The conducting polymer, poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid (PEDOT:PSS), is certainly one of the most important substitute materials for indium tin oxide in organic devices. Its metallic conductivity and transmittance bring favorable perspectives for organic photovoltaic applications. Although graphene oxide (GO) is not a good conductor, it can form high-quality thin films and can be transparent, and additionally, GO is an inexpensive material and can be easily synthesized. This study investigated how the conductivity of a composite film of graphene oxide (GO) and different amounts of PEDOT:PSS can be modified. The effects of GO:PEDOT:PSS composites with several PEDOT:PSS proportions were analyzed in regards to the composite molecular structure and ordering, charge transfer dynamics (in the femtosecond range), electrical properties and morphology. For the best conductivity ratio GO found with 5% PEDOT:PSS, a solvent treatment was also performed, comparing the resistivity of the film when treated with dimethyl sulfoxide (DMSO) and with ethylene glycol.

Poly(3,4-ethyledioxythiophene), or PEDOT, is a well-known polymer used in organic electronics due to its high electrical conductivity, flexibility and optical transparency. This study proposes a simple and fast method to obtain a conductive ink based on PEDOT aqueous dispersion, stable for months without surfactants, polymers, or additives, formed by polymer nanoparticles with low metallic content. PEDOT was obtained by oxidative polymerization of the monomer with anhydrous iron(III) chloride in acetonitrile. The obtained solid was washed and the residue content is decreased to lower than 0.5%. Fresh polymerized and wet PEDOT was sonicated in water and resulted in aqueous ink with concentration up to 1.145 g L−1, stabilized by electrostatic repulsion. This conductive ink was deposited via air-brush technique on glass substrates and has formed conductive and transparent thin films with sheet resistances of 1 and 20 kΩ sq−1 and transmittances at 550 nm of 50% and 80% respectively. Those electrodes have PEDOT distributed over macroscopic distances and recovering the entire substrates, which shows the great potential of the aqueous PEDOT ink as well as the deposition technique to be used in organic electronic devices.

We report a novel pKa determination for different graphene-like samples: graphene oxide (GO), reduced GO (rGO), graphene nanoribbons (GNR), oxidized GNR (GONR), thiol- and imidazole-functionalized GO (GOSH and GOIMZ, respectively) and thiol-functionalized GONR (GONRSH). Using the specialized computational program BEST7 for treating titration curves, pKas for different functional groups were discriminated (confirmed by infrared spectra) and their composition quantified. Overall, three equilibria were distinguished, two relative to carboxylic acids exhibiting different acidic degrees (pKa1∼4.0 and pKa2∼6.0) and one relative to alcohols (pKa4∼10.0). Upon functionalization on carboxylate sites, thiol (pKa(GOSH/GONRSH)=6.7) and imidazole (pKa(GOIMZ)=6.6) moieties were discerned, followed by a decrease of their carboxylate percentage (compared to the precursors), thus allowing determining the degree of functionalization (48% and 36% of thiol content for GOSH and GONRSH respectively, and 29% of imidazole for GOIMZ). The proposed method is innovative and simpler when compared to the traditional tools usually employed to quantify chemical functionalization.

Hexagonal close packed (hcp) nickel nanoparticles stabilized by polyvinylpyrrolidone (PVP) were synthesized through the thermal treatment of face centered cubic (fcc) nickel nanoparticles. Controlling both the temperature of the heat treatment and the amount of PVP was possible the control of the hcp/fcc rate in the samples, where the higher Ni/PVP ratio produces only the hcp-nickel phase (average size of 8.9 nm) highly stable in air. The crystalline structure, the presence of PVP, the size of the nanoparticles and the stability of the hcp-nickel were confirmed using X-ray diffractometry, Fourier transform infrared spectroscopy, transmission electron microscopy, Raman spectroscopy, scanning electron microscopy and thermogravimetric analysis. Thin films of hcp and fcc nickel nanoparticles were prepared through a biphasic system and deposited over indium-doped tin oxide (ITO) substrates, which were electrochemically characterized and applied as glycerol amperometric sensors in NaOH medium. Parameters as the number of cycles applied and the scan rate were evaluated and indicate that hcp nickel nanoparticles are more reactive to form Ni(OH)2 and lead to more electroactive Ni(OH)2 structure. The hcp nickel nanoparticles-modified electrode showed the best sensitivity (0.258 μA L μmol(-1)) and detection limit (2.4 μmol L(-1)) toward glycerol.

Transparent, flexible and conductive thin films of reduced graphene oxide or different types of carbon nanotubes have been prepared through the liquid-liquid interfacial method, and deposited over two different substrates, glass or polyethylene terephthalate (PET). Sheet resistance, morphology, transmittance and electrochemical measurements of the films have been evaluated in order to verify potential application as transparent electrodes. The effect of the amount of carbon nanostructures on the properties of the films, as well as the effect of the annealing treatment at different temperatures, has been also evaluated. Results shown that all films can be successfully used as electrodes, presenting optimized sheet resistances ranging from 1.7 to 50 kΩ/□ and transmittances at 550 nm up to 85 %. Flexible and transparent electrodes presenting high stability have been obtained by the carbon nanostructure films deposited over PET. A modification of the electrodes has been demonstrated, through an electropolymerization of aniline, confirming the potential for further application as flexible devices.

Multi-walled carbon nanotubes (MWCNTs) filled with different species of cobalt (metallic cobalt, cobalt oxide) were synthesized by a chemical vapor deposition method through cobaltocene pyrolysis. A systematic study was performed to correlate different experimental conditions with the structure and characteristics of the obtained material. Thin films of Co-filled CNTs were deposited over conductive substrates through a liquid-liquid interfacial method and were used for cobalt hexacyanoferrate (CoHCFe) electrodeposition by an innovative route in which the Co species encapsulated in the CNTs were employed as reactants. The CNT/CoHCFe films were characterized by different spectroscopic, microscopic, and electrochemical techniques and presented high electrochemical stability in different media. The nanocomposites were applied as both an electrochemical sensor to H2 O2 and a cathode for ion batteries and showed limits of detection at approximately 3.7 nmol L(-1) and a capacity of 130 mAh g(-1) at a current density of 5 A g(-1) .